An organic thin film transistor (OTFT) is a semiconductor device which uses an organic semiconductor material in place of a conventional silicon semiconductor material. Compared with silicon based materials, an organic material is difficult to fabricate and of high-cost. However, an organic material can be prepared to be in a solution, and used to prepare semiconductor devices under mild conditions, and thus it receives more attention, and has become a core element in the next-generation display technology. At present, Samsung, Sony and many other display manufactures have conducted the development of integrated circuits based on organic thin film transistors. An organic thin film transistor, by virtue of its flexible characteristics, becomes an indispensable technical element in a foldable display and a panoramic display screen.
Since an organic semiconductor thin film usually has a relative large volume conductivity, if the organic semiconductor thin films of thin film transistor devices in an integrated circuit are interconnected with each other, then, on the one hand, it is easy to generate crosstalk between adjacent devices, and on the other hand, the leakage electric-current of the devices will greatly increase, resulting in decrease of ON/OFF current ratio. These problems seriously hindered the applications of OTFT devices in large-area arrays and integrated circuits.
Dewetting-patterning method is a process conducted by changing the surface energy of a substrate, so that an organic solution of a semiconductor material can be selectively remained on the surface of the substrate, achieving the patterning of a semiconductor thin film. This method can uniformly alter the surface energy of the substrate, such as difference among contact-angles on the entire surface of the substrate at various regions is within 5°, can be used to prepare micro-patterns of high precision, and has characteristics of fast preparation and mild preparation environment, etc., and thus has attained the attention of academia and become the research focus of pattering semiconductor materials.
At present, the organic solution of an semiconductor material is coated on the surface of the substrate mainly by adopting a drop standing method and a spin-coating method. The devices fabricated by the drop standing method possess a fatal flaw in the structure, because the semiconductor material is prepared in a solution, the flowing solution cannot stay in the regions with low surface energy, but stays in the regions with high surface energy. However, the regions with high surface energy of the substrate have a lot of hydrophilic hydroxyl groups, and these groups may react with carriers, so that carrier traps are generated and the mobilities of the carriers are hindered, thus the performance of the device is largely lowered and a big lag phenomenon exists.